Civil Engineering Reference
In-Depth Information
Installations building
being constructed
tubes and the closing of the openings in the roof of the caisson were carried
out with prefabricated beams.
The section of the northern access ramp which connects to the caisson, was
constructed within a construction pit with anchored sheet piling. Due to
the fact that a water-braking soil deposit was missing and large-scale and
lengthy drainage was not permitted, a bottom sealing of underwater con-
crete was applied in the deeply situated compartment of the construction pit
(sections 2 through 11). This sealing, which was anchored by means of
tension piles, has a thickness which varies from 1.40 metres to 1.10 metres.
In the compartment situated higher (sections 12 through 16), a temporary
drainage had to be applied between the sheet pile walls.
After the sheet pile walls and the anchoring was applied, the deep compart-
ment of the construction pit was excavated dry down to 4 metres
Fig. 8.11
NAP, in
which use was made of the water-braking deposit situated at 8 metres
NAP.
Then the pit was filled with water, which had an over-value of 0.15 metres
above the rise height of the aquiferous pack, and the excavation was con-
tinued in the wet.
For the design of the pile foundation and the choice of the type of pile, the
presence of the extremely compacted glauconitic siltish sand starting at
a depth of 19 metres
NAP, was important. Based on the high cone values,
a pile toe level deeper than 23 metres
NAP was considered as not
implementable.
Dependent on the piling grid, the occurring tensile force and the thus associ-
ated pile toe level, prefabricated concrete piles (450
450 mm) and Vibro-
composite piles (with a diameter of 508 mm with prefabricated elements
of 320
320 mm) were used.The prefabricated concrete piles were applied in
the section situated higher, where the required piling depth into the glauconitic
sand was minor (approximately 1 metre). The Vibro-composite piles were
applied in the deep section where the driving depth measured 3 metres to
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